1. Field of the Invention
The present invention relates generally to assembly carrier line systems, particularly to controlled carrier means and methods for carrying and orienting products or workpieces in a desired line of travel for machine or station processing.
2. Description of the Related Art
In some prior art assembly line systems, workpieces are carried on carriers, commonly pallets or pucks, that run along an assembly line in frictional engagement with an underlying support conveyor means usually the form of a rubber belt or cardanic chain. The use of pallets or pucks of various shapes for conveying discrete products has been in practice for some time. Such carriers increase product design flexibility, since the product design is not be limited by a need for the particular good to be provided with product conveying and orienting characteristics such as pins provided on the product, a flat formed on the product, or a peripheral seam of the product. Such carriers thus enable the conveying of products which are odd shaped, fragile, or which lack stability while also eliminating shingling (vertical or horizontal overlapping of products), squirting (vertical displacement due to product-to-product contact), scuffing, denting, breakage, and jams during assembly line conveying procedure.
Particularly in assembly carrier line operations wherein the carriers are not required to accommodate a variety of specific product orientations, one or more machine stations are employed parallel to the carriers to perform defined systematic operations upon the product. Such operations typically have several disadvantages including the serial line thru-put of carriers being subject to random product surging or accumulation, and the rate of carrier serial line thru-put being a function of the slowest machine or station in the line. Still further, the machine or station operations are usually limited to the initial product orientation set early in the line procedure which is maintained throughout the line. A need therefore exists for rapid repetitive assembly line processing of carrier borne products or workpieces to accommodate multiple machine or station operations which require differing specific orientations of the product or workpieces at selected points of the overall assembly line processing procedure.
An attempt to address this need can be found in U.S. Pat. No. 4,664,248 which discloses a device and method for specifically orienting and conveying products and in a common direction of travel that employs a plurality of identical, circular, product-carrying pucks having a flat conveyor contacting bottom surface and at least one circular peripheral surface contactable by corresponding circular peripheral surfaces of other pucks when located in a random surge thereof. Each puck is surmounted by a product support. Between its bottom surface and its product support, each puck has a peripheral slide surface parallel to the desired direction of travel of the oriented puck and at least one peripheral rotation producing surface, the slide and peripheral producing surfaces being inset from the circular peripheral surface. A conveyor is provided having in association therewith at least one external contact surface to engage the rotation producing surface of each puck and an alignment rail having an alignment edge to contact the slide surface of each puck. Each puck is conveyed past the at least one contact surface which cooperates with the at least one rotation producing surface to cause rotation of the puck until the alignment edge of the alignment rail contacts the puck slide surface to stop rotation of the puck in the desired orientation and to maintain this orientation of the puck as it is conveyed to the next workstation. However, the piece-part manipulation of product or workpieces of this carrier line operation is based upon the linear motion and rotational motion of the carrier parallel to the direction of carrier travel, not perpendicular to the linear direction of travel. Such a system does not expose both a side surface and bottom surface of the thing to be transported to workstations or other assembly line system processing.